title: Biocontrol of Escherichia coli O157: H7 on fresh-cut leafy greens.
abstract: The effect of a bacteriophage cocktail (EcoShield™) that is specific againstEscherichia coliO157:H7 was evaluated against a nalidixic acid-resistant enterohemorrhagicE. coliO157:H7 RM4407 (EHEC) strain on leafy greens stored under either (1) ambient air or (2) modified atmosphere (MA; 5% O2/35% CO2/60% N2). Pieces (~2 × 2 cm2) of leafy greens (lettuce and spinach) inoculated with 4.5 log CFU/cm2EHEC were sprayed with EcoShield™ (6.5 log PFU/cm2). Samples were stored at 4 or 10°C for up to 15 d. On spinach, the level of EHEC declined by 2.38 and 2.49 log CFU/cm2at 4 and 10°C, respectively, 30 min after phage application (p ≤ 0.05). EcoShield™ was also effective in reducing EHEC on the surface of green leaf lettuce stored at 4°C by 2.49 and 3.28 log units in 30 min and 2 h, respectively (p ≤ 0.05). At 4°C under atmospheric air, the phage cocktail significantly (p ≤ 0.05) lowered the EHEC counts in one day by 1.19, 3.21 and 3.25 log CFU/cm2on spinach, green leaf and romaine lettuce, respectively compared with control (no bacteriophage) treatments. When stored under MA at 4°C, phages reduced (p ≤ 0.05) EHEC populations by 2.18, 3.50 and 3.13 log CFU/cm2, on spinach, green leaf and romaine lettuce. At 10°C, EHEC reductions under atmospheric air storage were 1.99, 3.90 and 3.99 log CFU/cm2(p ≤ 0.05), while population reductions under MA were 3.08, 3.89 and 4.34 logs on spinach, green leaf and romaine lettuce, respectively, compared with controls (p ≤ 0.05). The results of this study showed that bacteriophages were effective in reducing the levels ofE. coliO157:H7 on fresh leafy produce, and that the reduction was further improved when produce was stored under the MA conditions.
authors.affiliation: Energy and Environmental Systems; College of Arts & Sciences; North Carolina A&T State University; Greensboro, NC USA ; Department of Family and Consumer Sciences; Food and Nutritional Sciences Program; North Carolina A&T State University; Greensboro, NC USA.
authors.forename: Olcay
authors.initials: O
authors.lastname: Boyacioglu
authors.forename: Manan
authors.initials: M
authors.lastname: Sharma
authors.forename: Alexander
authors.initials: A
authors.lastname: Sulakvelidze
authors.forename: Ipek
authors.initials: I
authors.lastname: Goktepe
keywords: E. coli  O157:H7; MAP; bacteriophage; leafy green; modified atmosphere packaging